Conventionally, various display devices such as a liquid crystal display (LCD) and the like have been developed. Further, a vehicle-mounted display device which is mounted on a vehicle has also been developed.
Recently, the use of a vehicle-mounted display device has extended to applications such as an instrument panel (instrument panel mounted on a dashboard) that performs liquid crystal display in full scale and a back monitor for displaying an image of a rear side of a vehicle, in addition to conventional navigation devices. Thus, the importance of information regarding a display operation when a driver drives a vehicle is on the rise.
In particular, as ISO26262 or the like, which is an international standard for functional safety regarding electricity/electronics of automobiles, has been established, the function of detecting an abnormality in display operation has become important.
Conventionally, when detecting an abnormality in display operation, an enable signal transmitted to the analog power supply circuit is merely monitored to determine whether an analog power supply circuit for driving a display panel (for example, an LCD panel) is in an enabled state.
However, in the method of monitoring the enable signal to the analog power supply circuit, when an abnormality occurs in the display operation due to driver abnormality or circuit abnormality on the display panel side in supplying power from the analog power supply circuit to a driver (load) that drives a display panel, the abnormality cannot be detected because the analog power supply circuit itself is in an enabled state.